β-alanine tanning of Drosophila cuticles and chitin

Abstract

The cuticular lamellae of the Drosophila melanogaster mutants, “ebony” (which fails to transport β-alanine into the cuticle during development) and “black” (which shows inhibited β-alanine synthesis) are wider and more diffuse than normal, and the endocuticular microfibrils lack distinctness. Injection of β-alanine into “black” induces normal compact lamellation and cuticular tanning. β-alanine readily forms tan colours when reacting with pure chitin or its saccharide monomer, N- acetyl-glucosamine (or glucose). Other dipolar omega amino acids do likewise. β-alanine is bound to pure chitin more rapidly than is l-alanine. Pre-treatment of chitin with β-alanine depresses subsequent binding of DOPA. Complexing of β-alanine with mucopolysaccharides or glycopolysaccharides may be responsible for inhibition of catabolism of glucose. Such inhibition is observed in Ehrlich ascites tumor cells in vitro.